| As one of the countries with the highest seismicity,China has to face various potential geological hazards induced by earthquakes in earthquake-prone areas.Among them,landslides,as the biggest secondary disaster phenomenon,have led to a trend of increasing disaster scale year by year.Therefore,the research on the disaster-causing mechanism of earthquake slopes has been one of the important research topics in the field of geotechnical earthquake engineering.It has become a real problem for the analysis and quantification of seismic landslide hazards,which needs to be figured out in regional disaster mitigation and land planning nowadays.However,due to the complexity of the dynamic instability of slopes under earthquakes,understanding the intrinsic mechanism is still far behind the practical needs.Moreover,when an earthquake occurs,the main shock is often followed by a series of aftershocks with varying magnitude.Thus,the cumulative impact of sequential earthquakes complicates the dynamic response characteristics of slopes,which makes the existing dynamic slope analysis and calculation methods for quantitative research full of difficulties and uncertainties.Against this background,the seismic response of slopes under complex seismic conditions was further investigated in this study.The physical phenomenon of truncated response due to the coupling of deformation and response in the dynamic action process was firstly analyzed and discussed.The change characterization of seismic response of slope as well as the performance of the truncation effect all were investigated.Then,on this basis,a regional seismic landslide hazard analysis was carried out to improve and revise the existing mapping methods.The corresponding research results can deepen the understanding of the disaster mechanism of dynamic slope instability and promote the existing seismic landslide hazard assessment system.The main research contents and results of this paper were as follows.(1)Firstly,centrifugal model shaking table tests were carried out on the seismic response of soil slopes under the action of mainshock-aftershock sequences.The effects of mainshockaftershock on homogeneous slopes with overlying saturated foundations and sandy slopes with inclined bedrock surfaces were investigated respectively.The law of response and deformation of slopes under impulsive-type mainshocks was completely analyzed.The effects of cumulative deformation due to aftershocks are highlighted.The experimental phenomenon of truncation induced by the coupling of response and deformation of the slope was mainly discussed together with the emphasized variation characteristics.(2)Then,the performance and effects of the response truncation effect were studied in detail.The intrinsic relationship between the truncation effect and the directionality of the response in the dynamic amplification analysis was discussed.It is clarified that the difference between the upslope and downslope should be taken into account in the dynamic analysis of the slope.Based on the full understanding of the response truncation effect,the mechanism of the response truncation effect was discussed and the calculation formula of truncation limit was established by the rigid block model and three stick-slip coupled models respectively.Subsequently,an approximate method considering the truncation effect for the calculation of dynamic response was proposed.(3)Finally,the variation law of seismic coefficients was recalculated by the idea of decoupling considering the effect of truncation.The research results of the slope above were applied to the improvement of the deterministic regional seismic landslide hazard mapping method.Then the deterministic regional analysis method was further extended using full probability calculation.The effects of the randomness of ground motion and the epistemic uncertainty associated with empirical models and input parameters were completely considered in the process of regional hazard analysis. |
